Joint International Conference on Long-term Experiments ...

THE INFLUENCE OF CHEMICAL AND BIOFERTILIZERS ON THE YIELD
AND NITROGEN CONTENT OF LETTUCE (LACTUCA SATIVA L.)
Andrea Balla Kovács, Ida Kincses, Imre Vágó, Rita Kremper
University of Debrecen Faculty of Agricultural Science
Department of Agricultural Chemistry and Soil Science
ABSTRACT
The greenhouse pot experiment on calcareous chernozem soil from Debrecen-Látókép
and on sandy soil from Újfehértó was performed to study the effects of biofertilizer in
the presence of reduced doses of chemical fertilizers on the yield and nitrogen content
of lettuce and the water soluble nitrogen forms (NO3 - and total-N) measured in 0.01 M
CaCl2 extracts. The experimental plant selected was cabbage head lettuce (Lactuca
sativa L.). The bi-factorial trials were arranged in a randomized complete block design
with four replications, applying four levels (0, 0.05, 0.1, 0.2 g pot -1 ) of N as NH4NO3
with or without application of biofertilizer as Phylazonit MC. P and K doses applied
were identical in all pots.
The results obtained suggested: Nitrogen doses markedly increased growth (fresh
and dry weight) of lettuce, had significant positive influence on N content of plant and
on values of NO3 - , total N measured in 0.01 M CaCl2 soil extract . Its increasing effect
was the same on two types of soils, only significance of variance varied.
The application of biofertilizer was not as effective as N doses and its effect was
dependent on soil caracteristics. The Phylazonit MC had an increasing influence, but
not significant effect on the fresh and dry weight of lettuce leaves and slightly changed
N content of plant. On chernozem soil, we have found an increasing effect in values of
N content of plant, NO3 - and total N measured in 0.01 M CaCl2 extracts. On the
contrary, on sandy soil a slight decreasing effect of biofertilizer was found in N content
of plant and total N measured in 0.01 M CaCl2. It seems that in our experiment, (over
the entire growing season) application of phylazonit on sandy soil might cause N
immobilization, in consequence decreased the mineral N fraction available for plant and
so decreased the N content of plant. To gain more, reliable applicability of Philazonit
MC, further studies are needed.
Keywords: lettuce, mineral fertilizers, nitrogen, biofertilizers
INTRODUCTION
Nitrogen as a major constituent of all plants is one of the most important nutrients. It
has got a unique position because relatively high amounts are required by most
agricultural crops for optimal yields (Black 1968, Stevenson and Cole 1999). Most
plants take up N as nitrate (NO3 - ) and ammonium (NH4 + ) from the soil solution
(Blackmer 2000). The use of nitrogen fertilizers is standard practice in vegetable
production systems. Increasing concern over nitrate contamination of soils, nitrate
leaching in groundwater and nitrate content in vegetable may require a reduction in N
application in crop production, while maintaining optimal productivity (Gutezeit and
Fink 1999). Lettuce is an important horticultural crop. High nitrate concentration in
leafy vegetables constitutes a health hazard and is therefore undesirable. Applications of
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